Even as casualties mount in Homs and elsewhere in Syria, a diplomatic impasse has largely blocked any international effort to stop the carnage.

Two Syrians evacuate an injured fellow opposition member in the northwestern… (Associated Press )

Reporting from Beirut —

A new round of fierce clashes and shelling was reported Wednesday in the battered Syrian city of Homs, while fresh recriminations flew aboutRussia'ssuddenly prominent role in the crisis.

Russian Prime Minister Vladimir Putin deplored what he called a growing "cult of violence" in international affairs, and emphasized that countries should have the opportunity to decide their own fates without interference from outside forces.

"Of course, we condemn any instance of violence, whatever side this comes from, but one cannot behave like a bull in a china shop," Putin said at a meeting in Moscow with Russian religious leaders, Interfax news agency reported.

Even as casualties mounted in Homs and elsewhere — a soaring human toll documented in amateur videos posted on the Internet — a diplomatic impasse has largely blocked any international effort to stop the carnage. The inaction has drawn expressions of outrage from the Syrian opposition and human rights advocates.

The United Nations High Commissioner for Human Rights, Navi Pillay, stressed in a statement Wednesday the "extreme urgency for the international community to cut through the politics and take effective action to protect the Syrian population."

But there was no prospect of any emergency international aid to Homs, though opposition representatives have called for such a mission.

Pillay said the U.N. Security Council's failure to take action had emboldened the government of President Bashar Assad "to massacre its own people in an effort to crush dissent."

The government denies shelling civilians and says it is engaged in a struggle with foreign-backed "terrorists" determined to overthrow the government. Syrian officials say that more than 2,000 security personnel have been killed since unrest broke out almost a year ago. The U.N. says the civilian death toll tops 5,000.

Opposition activists said government forces unleashed some of the fiercest shelling to date on Homs,Syria'sthird-largest city, sections of which have been turned into rubble-strewn war zones after months of fighting. The opposition has reported six consecutive days of shelling that have left scores of civilians killed.

"There are no ambulances, people are just dying," said one opposition activist reached via Skype in Homs, a stronghold of the rebel Free Syrian Army. "Every day is worse than the day before. The world is responsible for what happens here because you gave Assad the permission to kill."

That was a reference to the joint Russian-Chinese veto Saturday of a Security Council resolution endorsing a plan for Assad to cede power. The Syrian government applauded the action and thanked Moscow and Beijing. But the Russian-Chinese veto has drawn outrage from Arab states, Turkey, the United States and other governments that have openly backed Assad's ouster.

Russia has portrayed itself as an honest broker seeking only to curb the violence. But some see the Russian action as a cynical bid to prop up a fellow autocrat and Cold War ally, while denying the West a political victory in the heart of the Arab world.

Washington and other capitals calling for Assad's resignation say the Russians' push for dialogue is too late. Several opposition groups have rejected talks with the Assad government.